Whether to spend billions of dollars acquiring a U.S. mobile operator lock, stock and barrel could prove to be one of the hardest calls Arun Sarin, chief executive officer (CEO) of Vodafone Group PLC, may ever have to make.

Sarin, just six months into his new job at Europe's largest mobile phone company, faces what could be one of the biggest opportunities of his career -- the prospect of acquiring AT&T Wireless Services Inc. and establishing a bridgehead in the important U.S. market. It could also be, undoubtedly, one of the biggest gambles he may ever take, especially if the financial community refuses to support the move.

Ever since AT&T Wireless, the third largest mobile phone company in the U.S., put itself on the block, Vodafone has been on the tip of nearly every expert's tongue as a likely buyer. And for an obvious reason: Vodafone, with a penchant for controlling companies fully, is a junior partner in Verizon Communications Inc., the largest U.S. wireless operator in which the Newbury, England, company has a 45 percent stake.

What's more, Vodafone is aligned with a company using a mobile phone technology, CDMA (Code Division Multiple Access), which is incompatible with its GSM (Global System for Mobile Communications) infrastructure. Synergy between the two networks is nearly zilch.

To buy or not to buy? That's the question Sarin eloquently sidestepped last month in a conference call to present the group's key performance indicators. Vodafone is watching developments in the U.S. "through the lens of shareholder value creation," the CEO said. "Nothing is imminent but our interest is high."

Even if Sarin isn't about to let the cat out of the bag before the Feb. 13 deadline for companies to submit their bids for AT&T Wireless, beginning at around US$30 billion, many industry observers expect him to enter the fray.

AT&T Wireless could, indeed, be the last opportunity for Vodafone to gain control of a U.S. operator with a GSM network, according to Michael Ransom, senior analyst with Current Analysis Inc. "It's kind of now or never," he said.

The other GSM operator, T-Mobile USA Inc., appears to be an unlikely seller. Kai-Uwe Ricke, CEO of Deutsche Telekom AG, which owns the U.S. operator, has repeatedly underscored his commitment to the North American market.

Vodafone's keen interest in taking full control of a U.S. operator -- and especially one with a GSM network -- is linked to the company's strategy of establishing a global brand, harmonized customer services and economies of scale in its phone and network infrastructure equipment, according to Ransom. "This is a company that preaches cross-border seamless services and harmonized customer interfaces," he said.

The company's Eurocall tariff plan, which offers discounts to customers phoning within the Vodafone network, and its Live mobile Internet service are some good examples of the operator's harmonization efforts, according to Ransom. "A key factor is having uniform back-office systems," he said.

Vodafone has also been able to achieve huge savings by purchasing equipment in volume, most recently to upgrade its networks with new 3G (third-generation) technology based on W-CDMA (Wideband-CDMA), a company spokesman said. Verizon, however, supports another variant of CDMA technology for its 3G upgrade.

Since coming on board, Sarin has focused heavily on improving operational efficiency, the company spokesman said.

Other analysts, however, have their doubts about the need for Vodafone to tie up substantial capital in a U.S. asset when its roaming arrangement with Verizon appears to be working just fine. "It will cost Vodafone lots of money to jump horses in mid-race," said Phil Kendall, principle analyst with Strategy Analytics Ltd.

The company's roaming agreement with Verizon, Kendall said, gives its European and Asian customers the ability to make calls in the U.S., provided they have tri-band phones, which have become very popular. Also, the two operators have collaborated on a PC card, which allows customers to use both GSM and CDMA technologies to send and receive data. "So it's not as if Vodafone has nothing to show for its stake in Verizon," he said.

Still, Kendall admits that under the current arrangement, Vodafone is creating zero brand identity in the U.S. and is also missing out on revenue opportunities by having to fork over a good chunk of money for using Verizon's infrastructure.

For their part, Vodafone investors have shown little enthusiasm about a U.S. acquisition, worried about its negative impact on earnings. One financial analyst said it will be difficult to convince shareholders that full ownership of a weaker player is better than a large stake in the market leader.

However, Japan's largest cellular telephone network operator, which holds a 16 percent stake in AT&T Wireless, said at the end of last month that it has yet to make up its mind on whether or not to make a bid for the U.S. company.

NTT DoCoMo acquired a stake in AT&T Wireless in January 2001, during the height of the 3G wireless frenzy, paying about $8 billion. Since then, the Japanese company has written off nearly its entire investment in the carrier, following a sharp drop in AT&T Wireless' share price.

The sale of AT&T Wireless is likely to continue a consolidation trend already evident in the U.S. While 12 different operators, mostly regional players, accounted for 80 percent of the subscribers at the end of 1988, six large national operators achieved the same 80 percent market penetration by the end of 2003, according to data from the EMC World Cellular Database. EMC is a unit of Informa UK Ltd.